/*
 * Copyright © 2018 Adobe Inc.
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Adobe Author(s): Michiharu Ariza
 */

#include "hb.hh"

#ifndef HB_NO_SUBSET_CFF

#include "hb-open-type.hh"
#include "hb-ot-cff1-table.hh"
#include "hb-set.h"
#include "hb-bimap.hh"
#include "hb-subset-plan.hh"
#include "hb-subset-cff-common.hh"
#include "hb-cff1-interp-cs.hh"

using namespace CFF;

struct remap_sid_t
{
  unsigned get_population () const { return vector.length; }

  void alloc (unsigned size)
  {
    map.alloc (size);
    vector.alloc (size, true);
  }

  bool in_error () const
  { return map.in_error () || vector.in_error (); }

  unsigned int add (unsigned int sid)
  {
    if (is_std_str (sid) || (sid == CFF_UNDEF_SID))
      return sid;

    sid = unoffset_sid (sid);
    unsigned v = next;
    if (map.set (sid, v, false))
    {
      vector.push (sid);
      next++;
    }
    else
      v = map.get (sid); // already exists
    return offset_sid (v);
  }

  unsigned int operator[] (unsigned int sid) const
  {
    if (is_std_str (sid) || (sid == CFF_UNDEF_SID))
      return sid;

    return offset_sid (map.get (unoffset_sid (sid)));
  }

  static const unsigned int num_std_strings = 391;

  static bool is_std_str (unsigned int sid) { return sid < num_std_strings; }
  static unsigned int offset_sid (unsigned int sid) { return sid + num_std_strings; }
  static unsigned int unoffset_sid (unsigned int sid) { return sid - num_std_strings; }
  unsigned next = 0;

  hb_map_t map;
  hb_vector_t<unsigned> vector;
};

struct cff1_sub_table_info_t : cff_sub_table_info_t
{
  cff1_sub_table_info_t ()
    : cff_sub_table_info_t (),
      encoding_link (0),
      charset_link (0)
   {
    privateDictInfo.init ();
  }

  objidx_t      encoding_link;
  objidx_t      charset_link;
  table_info_t  privateDictInfo;
};

/* a copy of a parsed out cff1_top_dict_values_t augmented with additional operators */
struct cff1_top_dict_values_mod_t : cff1_top_dict_values_t
{
  void init (const cff1_top_dict_values_t *base_= &Null (cff1_top_dict_values_t))
  {
    SUPER::init ();
    base = base_;
  }

  void fini () { SUPER::fini (); }

  unsigned get_count () const { return base->get_count () + SUPER::get_count (); }
  const cff1_top_dict_val_t &get_value (unsigned int i) const
  {
    if (i < base->get_count ())
      return (*base)[i];
    else
      return SUPER::values[i - base->get_count ()];
  }
  const cff1_top_dict_val_t &operator [] (unsigned int i) const { return get_value (i); }

  void reassignSIDs (const remap_sid_t& sidmap)
  {
    for (unsigned int i = 0; i < name_dict_values_t::ValCount; i++)
      nameSIDs[i] = sidmap[base->nameSIDs[i]];
  }

  protected:
  typedef cff1_top_dict_values_t SUPER;
  const cff1_top_dict_values_t *base;
};

struct top_dict_modifiers_t
{
  top_dict_modifiers_t (const cff1_sub_table_info_t &info_,
                        const unsigned int (&nameSIDs_)[name_dict_values_t::ValCount])
    : info (info_),
      nameSIDs (nameSIDs_)
  {}

  const cff1_sub_table_info_t &info;
  const unsigned int    (&nameSIDs)[name_dict_values_t::ValCount];
};

struct cff1_top_dict_op_serializer_t : cff_top_dict_op_serializer_t<cff1_top_dict_val_t>
{
  bool serialize (hb_serialize_context_t *c,
                  const cff1_top_dict_val_t &opstr,
                  const top_dict_modifiers_t &mod) const
  {
    TRACE_SERIALIZE (this);

    op_code_t op = opstr.op;
    switch (op)
    {
      case OpCode_charset:
        if (mod.info.charset_link)
          return_trace (FontDict::serialize_link4_op(c, op, mod.info.charset_link, whence_t::Absolute));
        else
          goto fall_back;

      case OpCode_Encoding:
        if (mod.info.encoding_link)
          return_trace (FontDict::serialize_link4_op(c, op, mod.info.encoding_link, whence_t::Absolute));
        else
          goto fall_back;

      case OpCode_Private:
        return_trace (UnsizedByteStr::serialize_int2 (c, mod.info.privateDictInfo.size) &&
                      Dict::serialize_link4_op (c, op, mod.info.privateDictInfo.link, whence_t::Absolute));

      case OpCode_version:
      case OpCode_Notice:
      case OpCode_Copyright:
      case OpCode_FullName:
      case OpCode_FamilyName:
      case OpCode_Weight:
      case OpCode_PostScript:
      case OpCode_BaseFontName:
      case OpCode_FontName:
        return_trace (FontDict::serialize_int2_op (c, op, mod.nameSIDs[name_dict_values_t::name_op_to_index (op)]));

      case OpCode_ROS:
        {
          /* for registry & ordering, reassigned SIDs are serialized
           * for supplement, the original byte string is copied along with the op code */
          op_str_t supp_op;
          supp_op.op = op;
          if ( unlikely (!(opstr.length >= opstr.last_arg_offset + 3)))
            return_trace (false);
          supp_op.ptr = opstr.ptr + opstr.last_arg_offset;
          supp_op.length = opstr.length - opstr.last_arg_offset;
          return_trace (UnsizedByteStr::serialize_int2 (c, mod.nameSIDs[name_dict_values_t::registry]) &&
                        UnsizedByteStr::serialize_int2 (c, mod.nameSIDs[name_dict_values_t::ordering]) &&
                        copy_opstr (c, supp_op));
        }
      fall_back:
      default:
        return_trace (cff_top_dict_op_serializer_t<cff1_top_dict_val_t>::serialize (c, opstr, mod.info));
    }
    return_trace (true);
  }

};

struct cff1_font_dict_op_serializer_t : cff_font_dict_op_serializer_t
{
  bool serialize (hb_serialize_context_t *c,
                  const op_str_t &opstr,
                  const cff1_font_dict_values_mod_t &mod) const
  {
    TRACE_SERIALIZE (this);

    if (opstr.op == OpCode_FontName)
      return_trace (FontDict::serialize_int2_op (c, opstr.op, mod.fontName));
    else
      return_trace (SUPER::serialize (c, opstr, mod.privateDictInfo));
  }

  private:
  typedef cff_font_dict_op_serializer_t SUPER;
};

struct cff1_cs_opset_flatten_t : cff1_cs_opset_t<cff1_cs_opset_flatten_t, flatten_param_t>
{
  static void flush_args_and_op (op_code_t op, cff1_cs_interp_env_t &env, flatten_param_t& param)
  {
    if (env.arg_start > 0)
      flush_width (env, param);

    switch (op)
    {
      case OpCode_hstem:
      case OpCode_hstemhm:
      case OpCode_vstem:
      case OpCode_vstemhm:
      case OpCode_hintmask:
      case OpCode_cntrmask:
      case OpCode_dotsection:
        if (param.drop_hints)
        {
          env.clear_args ();
          return;
        }
        HB_FALLTHROUGH;

      default:
        SUPER::flush_args_and_op (op, env, param);
        break;
    }
  }
  static void flush_args (cff1_cs_interp_env_t &env, flatten_param_t& param)
  {
    str_encoder_t  encoder (param.flatStr);
    for (unsigned int i = env.arg_start; i < env.argStack.get_count (); i++)
      encoder.encode_num_cs (env.eval_arg (i));
    SUPER::flush_args (env, param);
  }

  static void flush_op (op_code_t op, cff1_cs_interp_env_t &env, flatten_param_t& param)
  {
    str_encoder_t  encoder (param.flatStr);
    encoder.encode_op (op);
  }

  static void flush_width (cff1_cs_interp_env_t &env, flatten_param_t& param)
  {
    assert (env.has_width);
    str_encoder_t  encoder (param.flatStr);
    encoder.encode_num_cs (env.width);
  }

  static void flush_hintmask (op_code_t op, cff1_cs_interp_env_t &env, flatten_param_t& param)
  {
    SUPER::flush_hintmask (op, env, param);
    if (!param.drop_hints)
    {
      str_encoder_t  encoder (param.flatStr);
      for (unsigned int i = 0; i < env.hintmask_size; i++)
        encoder.encode_byte (env.str_ref[i]);
    }
  }

  private:
  typedef cff1_cs_opset_t<cff1_cs_opset_flatten_t, flatten_param_t> SUPER;
};

struct range_list_t : hb_vector_t<code_pair_t>
{
  /* replace the first glyph ID in the "glyph" field each range with a nLeft value */
  bool complete (unsigned int last_glyph)
  {
    hb_codepoint_t all_glyphs = 0;
    unsigned count = this->length;
    for (unsigned int i = count; i; i--)
    {
      code_pair_t &pair = arrayZ[i - 1];
      unsigned int nLeft = last_glyph - pair.glyph - 1;
      all_glyphs |= nLeft;
      last_glyph = pair.glyph;
      pair.glyph = nLeft;
    }
    bool two_byte = all_glyphs >= 0x100;
    return two_byte;
  }
};

struct cff1_cs_opset_subr_subset_t : cff1_cs_opset_t<cff1_cs_opset_subr_subset_t, subr_subset_param_t>
{
  static void process_op (op_code_t op, cff1_cs_interp_env_t &env, subr_subset_param_t& param)
  {
    switch (op) {

      case OpCode_return:
        param.current_parsed_str->add_op (op, env.str_ref);
        param.current_parsed_str->set_parsed ();
        env.return_from_subr ();
        param.set_current_str (env, false);
        break;

      case OpCode_endchar:
        param.current_parsed_str->add_op (op, env.str_ref);
        param.current_parsed_str->set_parsed ();
        SUPER::process_op (op, env, param);
        break;

      case OpCode_callsubr:
        process_call_subr (op, CSType_LocalSubr, env, param, env.localSubrs, param.local_closure);
        break;

      case OpCode_callgsubr:
        process_call_subr (op, CSType_GlobalSubr, env, param, env.globalSubrs, param.global_closure);
        break;

      default:
        SUPER::process_op (op, env, param);
        param.current_parsed_str->add_op (op, env.str_ref);
        break;
    }
  }

  protected:
  static void process_call_subr (op_code_t op, cs_type_t type,
                                 cff1_cs_interp_env_t &env, subr_subset_param_t& param,
                                 cff1_biased_subrs_t& subrs, hb_set_t *closure)
  {
    byte_str_ref_t    str_ref = env.str_ref;
    env.call_subr (subrs, type);
    param.current_parsed_str->add_call_op (op, str_ref, env.context.subr_num);
    closure->add (env.context.subr_num);
    param.set_current_str (env, true);
  }

  private:
  typedef cff1_cs_opset_t<cff1_cs_opset_subr_subset_t, subr_subset_param_t> SUPER;
};

struct cff1_private_dict_op_serializer_t : op_serializer_t
{
  cff1_private_dict_op_serializer_t (bool desubroutinize_, bool drop_hints_)
    : desubroutinize (desubroutinize_), drop_hints (drop_hints_) {}

  bool serialize (hb_serialize_context_t *c,
                  const op_str_t &opstr,
                  objidx_t subrs_link) const
  {
    TRACE_SERIALIZE (this);

    if (drop_hints && dict_opset_t::is_hint_op (opstr.op))
      return_trace (true);

    if (opstr.op == OpCode_Subrs)
    {
      if (desubroutinize || !subrs_link)
        return_trace (true);
      else
        return_trace (FontDict::serialize_link2_op (c, opstr.op, subrs_link));
    }

    return_trace (copy_opstr (c, opstr));
  }

  protected:
  const bool desubroutinize;
  const bool drop_hints;
};

struct cff1_subr_subsetter_t : subr_subsetter_t<cff1_subr_subsetter_t, CFF1Subrs, const OT::cff1::accelerator_subset_t, cff1_cs_interp_env_t, cff1_cs_opset_subr_subset_t, OpCode_endchar>
{
  cff1_subr_subsetter_t (const OT::cff1::accelerator_subset_t &acc_, const hb_subset_plan_t *plan_)
    : subr_subsetter_t (acc_, plan_) {}

  static void complete_parsed_str (cff1_cs_interp_env_t &env, subr_subset_param_t& param, parsed_cs_str_t &charstring)
  {
    /* insert width at the beginning of the charstring as necessary */
    if (env.has_width)
      charstring.set_prefix (env.width);

    /* subroutines/charstring left on the call stack are legally left unmarked
     * unmarked when a subroutine terminates with endchar. mark them.
     */
    param.current_parsed_str->set_parsed ();
    for (unsigned int i = 0; i < env.callStack.get_count (); i++)
    {
      parsed_cs_str_t *parsed_str = param.get_parsed_str_for_context (env.callStack[i]);
      if (likely (parsed_str))
        parsed_str->set_parsed ();
      else
        env.set_error ();
    }
  }
};

namespace OT {
struct cff1_subset_plan
{
  cff1_subset_plan ()
  {
    for (unsigned int i = 0; i < name_dict_values_t::ValCount; i++)
      topDictModSIDs[i] = CFF_UNDEF_SID;
  }

  void plan_subset_encoding (const OT::cff1::accelerator_subset_t &acc, hb_subset_plan_t *plan)
  {
    const Encoding *encoding = acc.encoding;
    unsigned int  size0, size1;
    unsigned code, last_code = CFF_UNDEF_CODE - 1;
    hb_vector_t<hb_codepoint_t> supp_codes;

    if (unlikely (!subset_enc_code_ranges.resize (0)))
    {
      plan->check_success (false);
      return;
    }

    supp_codes.init ();

    code_pair_t glyph_to_sid_cache {0, HB_CODEPOINT_INVALID};
    subset_enc_num_codes = plan->num_output_glyphs () - 1;
    unsigned int glyph;
    auto it = hb_iter (plan->new_to_old_gid_list);
    if (it->first == 0) it++;
    auto _ = *it;
    for (glyph = 1; glyph < num_glyphs; glyph++)
    {
      hb_codepoint_t old_glyph;
      if (glyph == _.first)
      {
        old_glyph = _.second;
        _ = *++it;
      }
      else
      {
        /* Retain the SID for the old missing glyph ID */
        old_glyph = glyph;
      }
      code = acc.glyph_to_code (old_glyph, &glyph_to_sid_cache);
      if (code == CFF_UNDEF_CODE)
      {
        subset_enc_num_codes = glyph - 1;
        break;
      }

      if (code != last_code + 1)
        subset_enc_code_ranges.push (code_pair_t {code, glyph});
      last_code = code;

      if (encoding != &Null (Encoding))
      {
        hb_codepoint_t  sid = acc.glyph_to_sid (old_glyph, &glyph_to_sid_cache);
        encoding->get_supplement_codes (sid, supp_codes);
        for (unsigned int i = 0; i < supp_codes.length; i++)
          subset_enc_supp_codes.push (code_pair_t {supp_codes[i], sid});
      }
    }
    supp_codes.fini ();

    subset_enc_code_ranges.complete (glyph);

    assert (subset_enc_num_codes <= 0xFF);
    size0 = Encoding0::min_size + HBUINT8::static_size * subset_enc_num_codes;
    size1 = Encoding1::min_size + Encoding1_Range::static_size * subset_enc_code_ranges.length;

    if (size0 < size1)
      subset_enc_format = 0;
    else
      subset_enc_format = 1;
  }

  bool plan_subset_charset (const OT::cff1::accelerator_subset_t &acc, hb_subset_plan_t *plan)
  {
    unsigned int  size0, size_ranges;
    unsigned last_sid = CFF_UNDEF_CODE - 1;

    if (unlikely (!subset_charset_ranges.resize (0)))
    {
      plan->check_success (false);
      return false;
    }

    code_pair_t glyph_to_sid_cache {0, HB_CODEPOINT_INVALID};

    unsigned num_glyphs = plan->num_output_glyphs ();

    if (unlikely (!subset_charset_ranges.alloc (hb_min (num_glyphs,
                                                        acc.num_charset_entries))))
    {
      plan->check_success (false);
      return false;
    }

    glyph_to_sid_map_t *glyph_to_sid_map = acc.cff_accelerator ?
                                           acc.cff_accelerator->glyph_to_sid_map.get_acquire () :
                                           nullptr;
    bool created_map = false;
    if (!glyph_to_sid_map && acc.cff_accelerator)
    {
      created_map = true;
      glyph_to_sid_map = acc.create_glyph_to_sid_map ();
    }

    auto it = hb_iter (plan->new_to_old_gid_list);
    if (it->first == 0) it++;
    auto _ = *it;
    bool not_is_cid = !acc.is_CID ();
    bool skip = !not_is_cid && glyph_to_sid_map;
    if (not_is_cid)
      sidmap.alloc (num_glyphs);
    for (hb_codepoint_t glyph = 1; glyph < num_glyphs; glyph++)
    {
      hb_codepoint_t old_glyph;
      if (glyph == _.first)
      {
        old_glyph = _.second;
        _ = *++it;
      }
      else
      {
        /* Retain the SID for the old missing glyph ID */
        old_glyph = glyph;
      }
      unsigned sid = glyph_to_sid_map ?
                     glyph_to_sid_map->arrayZ[old_glyph].code :
                     acc.glyph_to_sid (old_glyph, &glyph_to_sid_cache);

      if (not_is_cid)
        sid = sidmap.add (sid);

      if (sid != last_sid + 1)
        subset_charset_ranges.push (code_pair_t {sid, glyph});

      if (glyph == old_glyph && skip)
      {
        glyph = hb_min (_.first - 1, glyph_to_sid_map->arrayZ[old_glyph].glyph);
        sid += glyph - old_glyph;
      }
      last_sid = sid;
    }

    if (created_map)
    {
      if ((!plan->accelerator && acc.cff_accelerator) ||
          !acc.cff_accelerator->glyph_to_sid_map.cmpexch (nullptr, glyph_to_sid_map))
      {
        glyph_to_sid_map->~glyph_to_sid_map_t ();
        hb_free (glyph_to_sid_map);
      }
    }

    bool two_byte = subset_charset_ranges.complete (num_glyphs);

    size0 = Charset0::get_size (plan->num_output_glyphs ());
    if (!two_byte)
      size_ranges = Charset1::get_size_for_ranges (subset_charset_ranges.length);
    else
      size_ranges = Charset2::get_size_for_ranges (subset_charset_ranges.length);

    if (size0 < size_ranges)
      subset_charset_format = 0;
    else if (!two_byte)
      subset_charset_format = 1;
    else
      subset_charset_format = 2;

    return true;
  }

  bool collect_sids_in_dicts (const OT::cff1::accelerator_subset_t &acc)
  {
    for (unsigned int i = 0; i < name_dict_values_t::ValCount; i++)
    {
      unsigned int sid = acc.topDict.nameSIDs[i];
      if (sid != CFF_UNDEF_SID)
      {
        topDictModSIDs[i] = sidmap.add (sid);
      }
    }

    if (acc.fdArray != &Null (CFF1FDArray))
      for (unsigned int i = 0; i < orig_fdcount; i++)
        if (fdmap.has (i))
          (void)sidmap.add (acc.fontDicts[i].fontName);

    return true;
  }

  bool create (const OT::cff1::accelerator_subset_t &acc,
               hb_subset_plan_t *plan)
  {
    /* make sure notdef is first */
    hb_codepoint_t old_glyph;
    if (!plan->old_gid_for_new_gid (0, &old_glyph) || (old_glyph != 0)) return false;

    num_glyphs = plan->num_output_glyphs ();
    orig_fdcount = acc.fdCount;
    drop_hints = plan->flags & HB_SUBSET_FLAGS_NO_HINTING;
    desubroutinize = plan->flags & HB_SUBSET_FLAGS_DESUBROUTINIZE;

    subset_charset = !acc.is_predef_charset ();
    if (!subset_charset)
      /* check whether the subset renumbers any glyph IDs */
      for (const auto &_ : plan->new_to_old_gid_list)
      {
        if (_.first != _.second)
        {
          subset_charset = true;
          break;
        }
      }

    subset_encoding = !acc.is_CID() && !acc.is_predef_encoding ();

    /* top dict INDEX */
    {
      /* Add encoding/charset to a (copy of) top dict as necessary */
      topdict_mod.init (&acc.topDict);
      bool need_to_add_enc = (subset_encoding && !acc.topDict.has_op (OpCode_Encoding));
      bool need_to_add_set = (subset_charset && !acc.topDict.has_op (OpCode_charset));
      if (need_to_add_enc || need_to_add_set)
      {
        if (need_to_add_enc)
          topdict_mod.add_op (OpCode_Encoding);
        if (need_to_add_set)
          topdict_mod.add_op (OpCode_charset);
      }
    }

    /* Determine re-mapping of font index as fdmap among other info */
    if (acc.fdSelect != &Null (CFF1FDSelect))
    {
        if (unlikely (!hb_plan_subset_cff_fdselect (plan,
                                  orig_fdcount,
                                  *acc.fdSelect,
                                  subset_fdcount,
                                  info.fd_select.size,
                                  subset_fdselect_format,
                                  subset_fdselect_ranges,
                                  fdmap)))
        return false;
    }
    else
      fdmap.identity (1);

    /* remove unused SIDs & reassign SIDs */
    {
      /* SIDs for name strings in dicts are added before glyph names so they fit in 16-bit int range */
      if (unlikely (!collect_sids_in_dicts (acc)))
        return false;
      if (unlikely (sidmap.get_population () > 0x8000)) /* assumption: a dict won't reference that many strings */
        return false;

      if (subset_charset && !plan_subset_charset (acc, plan))
        return false;

      topdict_mod.reassignSIDs (sidmap);
    }

    if (desubroutinize)
    {
      /* Flatten global & local subrs */
      subr_flattener_t<const OT::cff1::accelerator_subset_t, cff1_cs_interp_env_t, cff1_cs_opset_flatten_t, OpCode_endchar>
                    flattener(acc, plan);
      if (!flattener.flatten (subset_charstrings))
        return false;
    }
    else
    {
      cff1_subr_subsetter_t       subr_subsetter (acc, plan);

      /* Subset subrs: collect used subroutines, leaving all unused ones behind */
      if (!subr_subsetter.subset ())
        return false;

      /* encode charstrings, global subrs, local subrs with new subroutine numbers */
      if (!subr_subsetter.encode_charstrings (subset_charstrings))
        return false;

      if (!subr_subsetter.encode_globalsubrs (subset_globalsubrs))
        return false;

      /* local subrs */
      if (!subset_localsubrs.resize (orig_fdcount))
        return false;
      for (unsigned int fd = 0; fd < orig_fdcount; fd++)
      {
        subset_localsubrs[fd].init ();
        if (fdmap.has (fd))
        {
          if (!subr_subsetter.encode_localsubrs (fd, subset_localsubrs[fd]))
            return false;
        }
      }
    }

    /* Encoding */
    if (subset_encoding)
      plan_subset_encoding (acc, plan);

    /* private dicts & local subrs */
    if (!acc.is_CID ())
      fontdicts_mod.push (cff1_font_dict_values_mod_t ());
    else
    {
      + hb_iter (acc.fontDicts)
      | hb_filter ([&] (const cff1_font_dict_values_t &_)
        { return fdmap.has (&_ - &acc.fontDicts[0]); } )
      | hb_map ([&] (const cff1_font_dict_values_t &_)
        {
          cff1_font_dict_values_mod_t mod;
          mod.init (&_, sidmap[_.fontName]);
          return mod;
        })
      | hb_sink (fontdicts_mod)
      ;
    }

    return !plan->in_error () &&
           (subset_charstrings.length == plan->num_output_glyphs ()) &&
           (fontdicts_mod.length == subset_fdcount);
  }

  cff1_top_dict_values_mod_t    topdict_mod;
  cff1_sub_table_info_t         info;

  unsigned int    num_glyphs;
  unsigned int    orig_fdcount = 0;
  unsigned int    subset_fdcount = 1;
  unsigned int    subset_fdselect_format = 0;
  hb_vector_t<code_pair_t>   subset_fdselect_ranges;

  /* font dict index remap table from fullset FDArray to subset FDArray.
   * set to CFF_UNDEF_CODE if excluded from subset */
  hb_inc_bimap_t   fdmap;

  str_buff_vec_t                subset_charstrings;
  str_buff_vec_t                subset_globalsubrs;
  hb_vector_t<str_buff_vec_t>   subset_localsubrs;
  hb_vector_t<cff1_font_dict_values_mod_t>  fontdicts_mod;

  bool          drop_hints = false;

  bool          gid_renum;
  bool          subset_encoding;
  uint8_t       subset_enc_format;
  unsigned int  subset_enc_num_codes;
  range_list_t  subset_enc_code_ranges;
  hb_vector_t<code_pair_t>  subset_enc_supp_codes;

  uint8_t       subset_charset_format;
  range_list_t  subset_charset_ranges;
  bool          subset_charset;

  remap_sid_t   sidmap;
  unsigned int  topDictModSIDs[name_dict_values_t::ValCount];

  bool          desubroutinize = false;
};
} // namespace OT

bool
OT::cff1::accelerator_subset_t::serialize (hb_serialize_context_t *c,
                                           struct OT::cff1_subset_plan &plan) const
{
  /* private dicts & local subrs */
  for (int i = (int) privateDicts.length; --i >= 0 ;)
  {
    if (plan.fdmap.has (i))
    {
      objidx_t  subrs_link = 0;
      if (plan.subset_localsubrs[i].length > 0)
      {
        auto *dest = c->push <CFF1Subrs> ();
        if (likely (dest->serialize (c, plan.subset_localsubrs[i])))
          subrs_link = c->pop_pack ();
        else
        {
          c->pop_discard ();
          return false;
        }
      }

      auto *pd = c->push<PrivateDict> ();
      cff1_private_dict_op_serializer_t privSzr (plan.desubroutinize, plan.drop_hints);
      /* N.B. local subrs immediately follows its corresponding private dict. i.e., subr offset == private dict size */
      if (likely (pd->serialize (c, privateDicts[i], privSzr, subrs_link)))
      {
        unsigned fd = plan.fdmap[i];
        plan.fontdicts_mod[fd].privateDictInfo.size = c->length ();
        plan.fontdicts_mod[fd].privateDictInfo.link = c->pop_pack ();
      }
      else
      {
        c->pop_discard ();
        return false;
      }
    }
  }

  if (!is_CID ())
    plan.info.privateDictInfo = plan.fontdicts_mod[0].privateDictInfo;

  /* CharStrings */
  {
    c->push<CFF1CharStrings> ();

    unsigned data_size = 0;
    unsigned total_size = CFF1CharStrings::total_size (plan.subset_charstrings, &data_size);
    if (unlikely (!c->start_zerocopy (total_size)))
       return false;

    auto *cs = c->start_embed<CFF1CharStrings> ();
    if (likely (cs->serialize (c, plan.subset_charstrings, &data_size)))
      plan.info.char_strings_link = c->pop_pack (false);
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  /* FDArray (FD Index) */
  if (fdArray != &Null (CFF1FDArray))
  {
    auto *fda = c->push<CFF1FDArray> ();
    cff1_font_dict_op_serializer_t  fontSzr;
    auto it = + hb_zip (+ hb_iter (plan.fontdicts_mod), + hb_iter (plan.fontdicts_mod));
    if (likely (fda->serialize (c, it, fontSzr)))
      plan.info.fd_array_link = c->pop_pack (false);
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  /* FDSelect */
  if (fdSelect != &Null (CFF1FDSelect))
  {
    c->push ();
    if (likely (hb_serialize_cff_fdselect (c, plan.num_glyphs, *fdSelect, fdCount,
                                           plan.subset_fdselect_format, plan.info.fd_select.size,
                                           plan.subset_fdselect_ranges)))
      plan.info.fd_select.link = c->pop_pack ();
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  /* Charset */
  if (plan.subset_charset)
  {
    auto *dest = c->push<Charset> ();
    if (likely (dest->serialize (c,
                                 plan.subset_charset_format,
                                 plan.num_glyphs,
                                 plan.subset_charset_ranges)))
      plan.info.charset_link = c->pop_pack ();
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  /* Encoding */
  if (plan.subset_encoding)
  {
    auto *dest = c->push<Encoding> ();
    if (likely (dest->serialize (c,
                                 plan.subset_enc_format,
                                 plan.subset_enc_num_codes,
                                 plan.subset_enc_code_ranges,
                                 plan.subset_enc_supp_codes)))
      plan.info.encoding_link = c->pop_pack ();
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  /* global subrs */
  {
    auto *dest = c->push <CFF1Subrs> ();
    if (likely (dest->serialize (c, plan.subset_globalsubrs)))
      c->pop_pack (false);
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  /* String INDEX */
  {
    auto *dest = c->push<CFF1StringIndex> ();
    if (likely (!plan.sidmap.in_error () &&
                dest->serialize (c, *stringIndex, plan.sidmap.vector)))
      c->pop_pack ();
    else
    {
      c->pop_discard ();
      return false;
    }
  }

  OT::cff1 *cff = c->allocate_min<OT::cff1> ();
  if (unlikely (!cff))
    return false;

  /* header */
  cff->version.major = 0x01;
  cff->version.minor = 0x00;
  cff->nameIndex = cff->min_size;
  cff->offSize = 4; /* unused? */

  /* name INDEX */
  if (unlikely (!c->embed (*nameIndex))) return false;

  /* top dict INDEX */
  {
    /* serialize singleton TopDict */
    auto *top = c->push<TopDict> ();
    cff1_top_dict_op_serializer_t topSzr;
    unsigned top_size = 0;
    top_dict_modifiers_t  modifier (plan.info, plan.topDictModSIDs);
    if (likely (top->serialize (c, plan.topdict_mod, topSzr, modifier)))
    {
      top_size = c->length ();
      c->pop_pack (false);
    }
    else
    {
      c->pop_discard ();
      return false;
    }
    /* serialize INDEX header for above */
    auto *dest = c->start_embed<CFF1Index> ();
    return dest->serialize_header (c, hb_iter (&top_size, 1), top_size);
  }
}

bool
OT::cff1::accelerator_subset_t::subset (hb_subset_context_t *c) const
{
  cff1_subset_plan cff_plan;

  if (unlikely (!cff_plan.create (*this, c->plan)))
  {
    DEBUG_MSG(SUBSET, nullptr, "Failed to generate a cff subsetting plan.");
    return false;
  }

  return serialize (c->serializer, cff_plan);
}


#endif
